The Scottish champions have accepted a £5million bid for the prolific 25-year old and R's boss Redknapp suggests the deal is basically done and dusted.
"It's all been agreed. I've not been dealing with it but the chief executive and the chairman have been dealing with Celtic," he told STV.
"Hopefully we're close to finally getting there but until it's done you're never sure.
"He's a player we've been chasing for a while and now we've agreed a deal with Celtic.
"We've followed him from his days at Gray's Athletic to Southend to Scunthorpe. Then he's gone and scored goals at the highest level with Celtic.
"So he's proved that he's a goalscorer and hopefully he can score some goals in the Championship now.
"I would love to see him being leading goalscorer in the Championship and hopefully that would mean us being promoted."