Both players missed Tuesday's 1-0 DFB-Pokal win over Frankfurt, attacking midfielder Reus absent because of a torn muscle in his right thigh sustained in the 5-1 victory at Werder Bremen last weekend.
Midfielder Bender was unavailable due to a thigh strain, but Klopp hinted that the pair may well feature at Signal Iduna Park on Saturday as Dortmund look to gain ground on second-placed Bayer Leverkusen.
"We will not take any risks," Klopp said. "But we do not want to stop anyone who feels fit."
Addressing the recovery of Reus, Klopp joked: "Who knows, maybe it's a good time for torn muscle fibres. They heal more quickly in this weather."
Gundogan has not featured for Dortmund since August, and Klopp admitted that the 23-year-old still "needs time" to return to full fitness.
Dortmund head into Saturday's game looking to end a run of four league outings at home without a win.
"It was a tight game (on Tuesday)," he explained. "If we want to win on Saturday, we need to be really good."
