The visitors were aided when the Betis defender Westermann picked up a red card late in the first half.
Barcelona came out firing in the second half and the Croatia international Ivan Rakitic gave his side the lead in the 50th minute.
Luis Suarez doubled his sides lead towards the end of the game to secure all three points for Luis Enrique’s side.
Turan made a muted appearance when he came on as a minute in the 86th minutes in place of Rakitic.
The Turkish international move to Barcelona from Atletico Madrid at the start of the season €37 million. Turan was unable to play first team football for the first six months of the season due to the transfer ban imposed on Barcelona.