The 19-year-old signed for the Black Cats for £8.1m from Ipswich Town in 2011 but with Wickham not featuring in the Premier League this season, O'Neill has revealed that he is prepared to allow the England Under-21 forward to leave on loan.
O'Neill said: "In recent weeks, Connor has done very well indeed. He's done well in training and I think he's very keen to do well in the team now. But of course there are a couple of centre-forwards barring his way at the minute.
"A couple of clubs have asked about him in terms of going on loan, and that's something I'll give some consideration to now. I wasn't going to do anything until after Tuesday night because we've been in the middle of a hectic programme.
"Maybe now, and I'm not just talking about Connor here, there are a couple of players I think need some games."
Wickham has scored just one goal in 19 appearances for Sunderland.