C340 pilot departing CMA on right downwind reports NMAC with Citation jet inbound for OXR. The right downwind was at the request of CMA Tower who also called the traffic.

Narrative

Took off from CMA airport in the afternoon. We requested a left downwind departure however CMA Tower indicated it would conflict with the Oxnard ILS; therefore instructed and cleared us for a right downwind departure. Specific instruction was given to make it a wide right crosswind. Sky was clear; however; ocean moisture and haze made for decreased visibility below 1;500 to 2;000 MSL (approximate). Upon departure from Runway 26; made right turn to crosswind at about 800 feet MSL to wide crosswind. Continued climb northbound; in departure. Tower indicated traffic; I believe 2 targets; one a fixed wing small single and the other a Cessna Citation. Continued climb north and while in turn to right downwind departure; saw something pass by very fast out of left window; at my altitude. It was a split second; but I had seen the jet pass off my left at what seemed like 50 to 100 feet away; but it was so fast; I wasn't sure. As I completed my turn to the downwind departure leg; I look back out my right rear windows and verified that it was the Citation that I had seen. Looking back; I think if I had not started the turn to the downwind leg that we would have collided; although I cannot be sure how close it was. I was a bit unnerved and startled by the occurrence; therefore said nothing to CMA Tower. I wish I had; as I would like to know if it was a near miss or not.