The government-chartered corporation that raises funds for student loans, yesterday changed its structure to encourage more banks and colleges to do business with it.

Sallie Mae, as the federally chartered Student Loan Marketing Association is known, eliminated the requirement that all of its clients own shares of the association's voting common stock.

The move should make it possible for Sallie Mae's shareholder/customers to cash in their stock and make it more attractive for new clients to do business with Sallie Mae, said Ross Kleinman, a corporate spokesman. These effects should "enhance our competitiveness in the marketplace," he said.

Sallie Mae's clients are financial and educational institutions eligible to participate in the federally insured Guaranteed Student Loan Program. The stockholder-owned corporation serves as the nation's major secondary market for student loans, buying insured student loans and providing other financial services to such institutions.

Under Sallie Mae's charter, only financial and educational institutions that are eligible to participate in the Guaranteed Student Loan Program may own the corporation's voting common stock. To raise additional capital, Sallie Mae sold nonvoting shares to the public in 1983; that stock is traded on the New York Stock Exchange. The nonvoting stock sells at a higher price than the voting stock, which can be purchased only by Sallie Mae clients.

In 1973, when it first was raising capital, Sallie Mae required that an institution own a certain number of shares of voting common stock to be a client.

Since the creation of the nonvoting stock, Sallie Mae has allowed clients to convert a portion of their voting shares to nonvoting shares.

Yesterday's rules change means new clients will not have to buy voting shares. Existing clients will not have to hold on to a minimum number of voting shares.

Eliminating the requirement also will allow all current holders of voting stock to participate in the upcoming period for converting their shares. The next such opportunity will occur sometime between this July 1 and June 30, 1987. During that time, Sallie Mae will accept 2.9 million to 5.8 million shares for conversion.

As of Dec. 31, there were approximately 1,300 beneficial owners of the corporation's 20.3 million voting common shares. Also at year-end, 20.9 million shares of nonvoting common shares were outstanding.