Keane, who joined Celtic on loan this time last year and Bentley have struggled to break into Redknapp's side this season and seem certain to leave White Hart Lane.
"David wants to go out on loan or move permanently," said Redknapp. "He has had a long spell of not playing. He is a great talent in my opinion but it is hard for him.
"David is a lad who finds it hard to motivate himself sometimes when he is out of the side. He has been unlucky. Aaron Lennon has been in great form.
"David needs to get out and play somewhere for his own career. It is a waste of his talent that he is not playing.
"Robbie is the same. He needs to play. He can play at the top level. A loan wouldn't be an option for Robbie now, it would need to be a permanent move."
Source: PA
Source: PA