The Secret Service wants criminal charges filed against AWOL Pvt. Ralph William Myers, who flew a small plane too close to President Reagan's helicopter. Garry Jenkins, agent in charge of the Los Angeles office, said the U.S. attorney is expected to decide this week whether to file them. Meanwhile, the Army sent a two-man team to Los Angeles to return Myers to Ft. Lewis, Wash., in the event the Secret Service released him. Myers, whose private pilot's license was revoked after his rented plane flew within a few hundred feet of the President's helicopter, was being held in the brig at Long Beach Naval Station.