Answer
Qadiani is a person belonging to the Qadiani faith. They are a group who claim to be Muslim, but have been classified as kaafir by the Ulama of the Ahlus sunnah wal Jamaah. They claim that their leader Goolam Ahmed Qadian was a prophet.
Murtad means a renegade ie. one who professed Islam at one stage thereafter turned apostate and left Islam.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai