The Morocco international is on-loan at QPR for the remainder of the season.
"He's had good spells, he's had bad spells. QPR wanted to send him back halfway through the loan at one stage," Redknapp told the Kilburn Times.
"I said 'we can't take him back, it's a season-long loan', so they were upset with that.
"But since Neil's been there, he's found some form and he's playing very well. And when he has good days, he's a world-beater - he's got great ability.
"When Adel puts it all together he can be an amazing player. I'm sure Neil's getting the best out of him now. Everybody else tried at QPR, but if anyone can sort him out it'll be Neil Warnock.
"Maybe he's responding to Neil's management style and he's getting the best out of him."