Congress averted a partial shutdown of the government today as the House and Senate yesterday approved an emergency four-day extension of current spending authority.

The reprieve was aimed at preventing disruption of government operations while House-Senate conferees continue work on a catchall spending bill for the rest of fiscal 1986 that will satisfy President Reagan.

With an extra four days of work, Congress gave up on its plans to adjourn for the year this weekend. But the delay also enhances prospects of action on several major measures, including the farm bill and deficit-reduction legislation, that could have been trampled in an adjournment rush.

The House gave swift approval to the emergency measure in late afternoon, and the Senate, which had pressed for the extension in the first place, followed suit in early evening. At the White House, a spokesman said Reagan would sign the extension.

The measure extends current funding until 6 p.m. Monday, when congressional leaders hope to have wrapped up the omnibus spending bill to finance government agencies for which Congress has failed to pass regular appropriations bills for the fiscal year that began Oct. 1.

House-Senate conferees on this "continuing resolution" reported progress in negotiating compromises on all but a few issues during the day. But it was clear as nightfall approached that they would fail to agree on the measure by midnight, when current interim funding was to expire.

"There is no way in the world we could finish tonight," said Rep. Silvio O. Conte (Mass.), ranking Republican on the House Appropriations Committee, as the emergency funding measure was whipped through without dissent, despite previous complaints about delay from Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.).

Without an agreement acceptable to the White House or further stopgap funding, government workers in agencies covered by the legislation were instructed to prepare for an orderly shutdown of their operations at midday today.

Agencies that would have been affected by the shutdown -- and could still be affected if an agreement is not reached by Monday -- included the departments of Defense, Treasury, Agriculture, Interior and Transportation as well as the White House and the General Services Administration.

Other departments and agencies are covered by appropriations bills that have been signed into law or are expected to be approved. Reagan yesterday signed the appropriations bill for the departments of Education, Labor, and Health and Human Services, and aides indicated he will sign the bill covering the departments of State, Justice and Commerce.

In all, the continuing resolution is expected to cover seven of the 13 regular appropriations bills.

Congress' job is complicated by White House objections to versions of the continuing resolution passed by the Senate and House. Presidential advisers contended that both bills would spend too much on domestic programs at the expense of defense and said they would recommend a veto unless Congress eliminated a long list of "objectionable provisions."

Yesterday, House-Senate conferees were mainly stalled on spending for the departments of Defense and Interior.

On defense, the conferees were reportedly considering a plan under which the Senate would give up resumption of nerve gas production and other specific proposals in exchange for an overall spending level close to what it had proposed. The House wanted to freeze defense spending, while the Senate wanted to allow an increase for inflation.

In a tentative agreement on foreign aid, the conferees settled on $15 billion, more than either chamber had approved and close to the figure sought by Reagan.

Despite earlier expectations of a veto confrontation, congressional leaders and administration officials appeared guardedly optimistic that an accord could be worked out. "They're trying very hard to work things out," said one official familiar with the deliberations.

In addition to the emergency spending measure, the House and Senate approved a bill extending several revenue measures, including one to continue the current cigarette tax at 16 cents a pack. Without the short-term extension, the levy would have dropped to 8 cents. A permanent extension of the 16-cent tax is contained in deficit-reduction legislation now in a House-Senate conference.