Police are searching for an armed robber that held a Bronx cab driver at gunpoint after being asked for his fare money.Herman Ortega says he was working for the Watson Cab Company Sunday night when the incident occurred. He says a man asked to be dropped off at Seward and Metcalf avenues. Ortega says when he reached the destination and asked for the fare, the man pulled out a gun, held it to his head and demanded money. He got away with $350.Ortega says he is glad he was not hurt but admits that he and other cab drivers risk their lives every day driving through dangerous neighborhoods. One cab driver says he was held up at gunpoint twice in one year, once by a woman and another time by a minor.Police say the armed robber remains at large. They are asking anyone with information to call the 43rd Precinct Detective Squad at (718) 542-5530.