President Ferdinand Marcos, faced with currents of criticism, including some from within his own political ranks, is showing signs of wanting to reach accommodation with opponents of his martial-law rule as the Phillippines prepares for municipal elections Wednesday.

Marcos' friends and political associates are putting out the word that he will meet soon with his old rival, former senator Benigno Aquino, whom he has kept imprisoned for seven years.

They say he is serious about wishing to discuss an Aquino plan that would ease the tougher parts of martial law and require free elections within two years.

"There is no possibility of ending martial alw, at least for two years," said a pro-Marcos politician who meets frequently with the president. "But I am convinced he will pick up on Aquino's plan, at least to study what good it could do."

Although they are wary in assessing his motives, some anti-Marcos leaders also say they sense he wants to open a channel for discussions, if only to allay criticism by giving the appearance of seeking accommodation.They attribute this to a combination of economic and political pressures that have been mounting in the past few months. One foreign diplomat said, "Marcos is just tired of defending martial law all the time."

Cardinal Jaime Sin, leader of the powerful Roman Catholic Church in the Philippines, has warned of serious trouble unless martial law is eased. Students have demonstrated on campus. There is growing economic unrest stemming from an annual inflation rate of more than 20 percent and a steady decline in real wages since Marcos imposed martial law in 1972.

Some longtime Marcos allies have defected. Jose Laurel, former speaker of the House of Representatives, broke with the president publicly last fall in a speech criticizing the Marcos life style in Malacanang Palace. Laurel is managing an opposition slate in Batangas Province's local elections this week.

In another bitter falling-out, Marcos fired a longtime aide, Information Minister Francisco Tatad, because Tatad insisted on naming a political slate in his home province of Catanduanes, southeast of the main island of Luzon. Marcos angrily denounced him as the "spoiled boy" of his Cabinet and by implication accused him of arrogance and corruption.

None of these troubles represent serious danger to Marcos' rule, observers here say, but they show a tide of dissent that is rising rather than falling. Marcos at times has seemed despondent. Last September he complained of a "return to the same cynicism that started the proclamation of martial law" and cited "the same corruption, the same dishonesty and the same self-centered selfishnes."'

He also has been called on repeatedly to deny a series of rumors that he is seriously ill. These rumors started after his face appeared to be puffed up, as though he had been taking strong medication. In several interviews last week, friends insisted Marcos, 62, is a healthy man who diets carefully and exercises regularly. He has maintained a vigorous schedule during the current local election campaigns. One friend said the facial pufines occurred in a brief period when Marcos, at the urging of his wife Imelda, had gone off his usual rigorous diet.

The Aquino plan for phasing out martial law was disclosed by Marcos early this month, at a time when the former opposition senator was at his home for a three-week holiday from his cell in Fort Bonifacio prison.

Marcos revealed the plan in an interview with the Bangkok Post. He said he would meet soon with Aquino to discuss his idea of setting up a "council of elders" to advise on martial law; which might include Aquino and two other well-known opposition leaders, Jose Diokno and Lorenzo Tanada. Marcos was quoted as saying he hoped to reach a "deliberate consensus."

Aquino, 47, had sent the idea privately to Marcos from his prison cell in October and was surprised when the president publicly disclosed it.

The other opposition leaders were critical. Diokno flatly rejected any cooperation while martial law is in effect. Tanada said last week he would not participate unless Marcos displayed "concrete signs of sincerity." That would include a return to press freedom, repeal of the suspension of habeas corpus, and a lifting of the ban on labor strikes.

Aquino incorporated Tanada's points and issued a full explanation of his plan that calls for a plebiscite on a new form of government in November 1981, and national elections a year later. Martial law would end on Jan. 1, 1983, when the new government took over.

To the surprise of many observers, Aquino advised his colleagues in the opposition to stop being so suspicious of the Marcos government and said that "good faith" is required in order to get any kind of dialogue underway.

Aquino returned to prison to mid-January without meeting with Marcos, but the president subsequently said he still plans to meet with him.

Marcos' associates said last weeek they expect the meeting to be held soon after Wednesday's local elections.