Quiepo can find you at the beginning of the game after having escaped the hotel in Pala. If so, he will awaken the player at the Cock-Fights then offer the tutorial mission in the form of your first assignment.
Either after a call from Reuben Oluwagembi, or the assassination of Oliver Tambossa, he will meet the player at the Marina bar, or at the APR headquarters in Mosate Selao, respectively, and assign a mission to kill Nick Greaves and Walton Purefoy, the other two APR lieutenants. You can complete his mission, allowing him to become the leader of the APR. Alternatively, you can kill just Greaves or just Purefoy — the remaining one will ask you to turn the tables on Quiepo. Even if you choose not to kill him, like all other potential faction leaders he is killed at the end of the game at the Jungle Bivouac.