Born in Bertoua, Cameroon, Keben moved to France at the age of 2 and at 5 started playing football at Toulouse Montaudran. At the age of 10, he joined the youth academy of Toulouse and started working his way up their youth sides. He was promoted to their reserves in 2021, and represented the senior side in a Coupe de France match over Aubagne. On 1 February 2022, he signed his first professional contract with Toulouse. On 7 August 2022, he made his professional debut with Toulouse in a 1–1 Ligue 1tie with OGC Nice, coming on as a substitute in the 79th minute.