President Reagan told Congress yesterday he will settle for about half his proposed domestic appropriations cuts, but the Senate Appropriations Committee ignored him and moved ahead with a catch-all spending bill for almost all the government which the president is expected to veto later this week.

In a letter to Senate Majority Leader Howard H. Baker Jr. (R-Tenn.), Reagan said he was "prepared to meet the Congress halfway" and endorsed a proposal advanced by House Minority Leader Robert H. Michel (R-Ill.) earlier in the week to save about $4 billion of the $8.4 billion that Reagan had wanted to cut from domestic appropriations.

Reagan's retreat came in the face of heavy congressional opposition to most of his latest proposals for budget cuts, leaving him with little more than veto threats to get what he could. In this context, the president said the Michel proposal, which the House rejected on Monday, would provide a "substantial share" of the savings he wants, and he urged the Senate to adopt a "similar approach."

But the Republican-controlled Appropriations Committee, voting 18 to 8, rejected a variation on the theme, proposed by Sen. Mack Mattingly (R-Ga.) with the encouragement of Baker, that would have cut an estimated $8 billion by slicing into defense and basic benefit or entitlement programs as well as domestic appropriations.

The entitlement cuts would have given Reagan limited powers of impoundment, prompting Sen. Thomas F. Eagleton (D-Mo.) to recall former president Nixon's fights with Congress over refusal to spend money and to complain that it was "the second coming of impoundment." But it wasn't only Democrats who voted against the proposal. Six Republicans did, too.

The Michel proposal was not offered, although sources said Senate Republican leaders see it as a likely fallback position for Congress to adopt if, as expected, Reagan vetoes the huge spending bill and the veto is sustained. It also could be brought up in the Senate when the bill reaches the floor today.

The Senate committee contends its bill would cost no more than $100 million more than Reagan proposed last September in urging a 12 percent cut in domestic appropriations, but administration budget officials indicated they think the overage is considerably greater. House Democrats also contend their bill comes close to Reagan's targets for domestic spending cuts and exceeds those targets when defense cuts are included.

Congress must pass the measure by Friday or current stopgap funding authority for the government will expire, leaving it without money to reopen on Monday. The interim funding is required because Congress has yet to pass any appropriations bills for the executive branch for the fiscal year that began last Oct. 1.

The expectation of a weekend White House-Congress shoot-out over the continuing resolution intensified in both Houses, with some Republicans as well as Democrats contending that Reagan wants a veto confrontation in order to get his troubled economic program back on the offensive.

A veto would "make him look like a macho man, I guess," said House Majority Leader James C. Wright (D-Tex.), asserting that it was part of a "cynical game plan" to set Congress up for blame if the economy is still faltering by the time of the 1982 elections.

"The clear signal from the administration is that they want to veto this thing," said a Senate Republican source who asked that his name not be used.

The way things stood yesterday it appeared that Reagan would indeed have something to veto by the weekend.

The House on Monday approved a bill that Reagan's Office of Management and Budget said made hardly any progress toward his goal of a 12 percent cut in domestic appropriations. As a possible compromise, Mattingly and other Senate Republicans pushed a 2 percent cut in all programs, including defense and big entitlement programs, that left Reagan some discretion in where to make the cuts.

But top White House officials rejected that approach, congressional sources said, in favor of the Michel proposal.

Reagan then confirmed his support for the Michel proposal in a letter to Baker that first asserted his position that "excessive appropriations measures simply cannot be tolerated--not now nor in the future" but then went on to say:

"Given the present legislative circumstances, however, I am prepared to meet the Congress halfway. The 5 percent across-the-board reduction to domestic discretionary programs . . . provides a substantial share of the fiscal year 1982 outlay savings I requested in September. I would urge you and your colleagues to adopt a similar approach to the second continuing resolution."

Nevertheless, Mattingly decided to push ahead with the 2 percent cut, holding Michel's proposal in reserve as a fallback strategy for giving Reagan what he wants if he vetoes the resolution and the veto is sustained by Congress.

Michel's proposal was defeated 201 to 189 in the House, close enough to assure that a veto would be sustained and to give the administration hope of switching enough votes to pass the proposal after the veto was sustained.

It takes only one-third plus one member of either house to sustain a presidential veto. A simple majority would be required for passage of a continuing resolution.

The 2 percent cut was estimated to save more than Michel's proposal: $6 billion to $9 billion as opposed to $4 billion. But, unlike Michel's proposal, it would cut entitlements and defense, which the administration opposes, at least at this time.

Meanwhile, the Senate passed by a vote of 57 to 33 the $7.3 billion foreign aid appropriation bill, even though its provisions will be overtaken by levels set in the continuing resolution.

The bill is exactly in line with the president's September budget request and includes a substantial increase in military assistance. Reflecting the administration's appeal for more emphasis on military aid, it includes an appropriation for arms sales and direct military grants that is $458 million higher than that in last year's budget.

Democrats contended the bill spends too much for military aid and too little for economic assistance. It represents a "fundamental misperception" of what causes instability in poor countries and represents a policy of "arms instead of bread," said Sen. Daniel K. Inouye (D-Hawaii).

Inouye also objected to a cut even below the president's September request in new money for the International Development Association, which makes soft loans to undeveloped nations. But he withdrew an amendment that would have put back into the bill enough money to match Reagan's target.