City Atty. Louise Renne of San Francisco has ordered her staff to prepare a sex discrimination lawsuit against the 128-year-old Olympic Club. In addition, Renne said she has asked the state Department of Alcoholic Beverage Control to determine whether the club's liquor license can be revoked on the basis of the alleged discrimination. The lawsuit would be the first legal test of a city anti-discrimination ordinance adopted in November, 1987. Club officials maintain that recent policy changes exempt the institution from the ordinance. The city ordinance bans discrimination against women and minorities by clubs that have more than 400 members, provide regular meal service and accept dues from members and expenses from nonmembers. The Olympic Club contends it is exempt because of minor changes it made in dues policies after the ordinance was adopted. The city sued the club once before, in 1987, demanding that it admit women and minorities or give up its lease of 17 acres of city-owned land at the club's Lakeside Country Club golf course.