Tony Melendez, the armless guitarist and singer who gave a three-minute miniset for Pope John Paul II during the pontiff's visit here last week, is learning the meaning of the term exposure . Reporters, concert promoters and agents from all over the world have contacted Melendez, the 25-year-old musician said after Mass Sunday at Our Lady of Guadalupe Church in Chino. "It's scary, because it has all happened so fast," Melendez told fellow parishioners. "I ask you to pray for me." Melendez said he has booked speaking engagements in Detroit and Spain and has been offered recording contracts from three labels.