The Hoops made their return to the Premier League on Saturday after winning promotion last season, but they fell to a 1-0 defeat against Hull City.
"We need to get a couple more in, we're short in some areas," Sky Sports News quotes Redknapp as saying. "I've got three central midfield players - Joey Barton, Alejandro Faurlin and Karl Henry - when you need six midfield players really, at this level.
"So we're looking to get one or two midfielders in and maybe a front man as well, because we need a bit of cover there. You need four strikers, in an ideal world.
"If you look at the whole squad, with everyone fit we've got 18 or 19 outfield players, and that includes one or two lads who couldn't get in the squad last year. We'll probably use the loan system again. Maybe we'll buy one and loan a couple."