The 29-year-old Mali international has been training with the Championship outfit for the last four weeks and has also featured in a number of Under-21 matches.
The defensive midfielder is currently a free agent after leaving the New England Revolution in August and could be given a deal by the Rams, according to McClaren.
"Kalifa is still with us and he is getting better and fitter each week," the Derby Telegraph quotes him as saying.
"He played at Huddersfield and did very well. We had a chat with him and we said to him 'keep training with us' - which he is happy to do - and we will see where it leads.
"It suits both parties. It is a win-win situation for both of us. The possibility of a short-term deal could be there. We'll see how it goes."