On behalf of the federal work force, the president's new budget asks Congress for what officials called modest increases in the number of employees and an "iffy" 6 percent pay raise. It also proposes an experimental program designed to "break down artificial barriers" to permanent part-time employment for people such as housewives and students who cannot work full-time.

The part-time employment initiative will require the government to account for its workers in a new way - in terms of employe hours instead of body counts. It is in line with the Carter administration's efforts generally to give federal managers more flexibility in hiring, firing and promoting their workers.

If successful, budget officials said, the new system "may ultimately be used as the primary means of controlling the sieze and makeup of the federal civilian work force."

Five agencies slated to participate in the initial experiment are the Veterans Administration, which has more than 195,000 employees and is the third largest agency; the General Services Administration, the Export-Import Bank, the Federal Trade Commission and the Environmental Protection Agency.

Of the approximately 2 million civilian executive branch workers affected by the budget (the Postal Service is not included), only about 38,000 currently are permanent part-time workers. Their pay and benefits are pro-rated on the basis of time worked.

The experiment sets no quotas for increasing the number but is supposed "to find out what number an agency finds sensible," Office of Management and Budget officials said.

The budget proposes a federal civilian payroll, including fringe benefits, of about $53.8 billion for fiscal 1979, an increase of more than $4.5 billion over 1978 (estimated) and more than $7.5 billion above the actual 1977 amount.

Much of the increase (almost $2 billion) is to cover a 6 percent pay raise for federal workers. However, the president has indicated that 5.9 per cent would be the top limit if he applies his new guidelines for voluntary wage and price controls. Some officials say the raise could be even less than that.

Workers will get more if the president sticks strictly to the statutory process designed to keep U.S. pay comparable to nonfederal pay for the same work. Budget analysts project that a raise of 6.5 percent would achieve that "comparability."

In any case, the president makes the final decision on how big a raise, if any, to give his workers and, officials added, he will not make up his mind until next August.

In the Washington area, about 300,000 white collar civil servants and an additional 80,000 uniformed military personnel benefit from the increases that traditionally kick in with October pay checks.

In addition, the administration is pushing legislation to limit future raises for the government's half-million blue collar workers, at an estimated saving to federal agencies of $45 million next year.

In terms of the number of jobs, the budget calls for an overall national increase of 1,500 positions over estimated 1978 employment levels. This represents an increase of 8,700 workers, divided among several agencies, which is offset by a decrease of 7,200 in civilian Defense Department workers, as officials summed it up.

While that increase from 1978 to 1979 is relatively small, officials said, "much larger increases are occurring" between actual employment in 1977 and estimated employment levels for 1978 - an increase of about 21,000.

The increases are necessary to help carry out new programs, and to meet the increasing workload demands of a growing population, according to budget analysts.

At the same time, noting the public's aversion to the idea of a mushrooming big government, officials emphasized that U.S. civilian employment is under 3 percent of the country's total civilian work force. That is down from a high of about 3.8 percent in 1968.