ASIA'S leading club sides may find themselves up against some of the world's most glamorous teams if a FIFA proposal is passed by the five confederations at the end of the year. FIFA, the sport's world governing body, hopes to stage a 16-team World Club Championship in late 1996. The two-week tournament would involve eight clubs from Europe and two each from South America, Asia, Africa and from the CONCAFAF region of North and Central America and the Caribbean. Peter Velappan, general secretary of the Asian Football Confederation, said the five confederations would meet in November or December to discuss the FIFA proposal. ''With the World Cup, the Olympic Games football tournament and the World Youth Championships all well established, FIFA feels that now is the time for the clubs,'' said Velappan. ''The AFC fully supports the proposal because it would be a tremendous boost for clubs in Asia.''