You should get him a family visit visa when he was still in the Philippines. You will have to pay only Qrs.200 for his entry visa and then extend it for a maximum of 6 months. But then, since he is here already the consequences for that is you have to let him go out Qatar (if he cannot find employer after a month) and get him visa under your sponsorship. A business visa can be obtained also but still your son need to go out before getting another sponsor with higher amount charged by the agency. Better you sponsor him personally it will cost lesser.Requirements of family visit visa can be reviewed from previous post under Visa and Permits forums.