Los Angeles International (LAX). From there to Las Vegas is 270 miles. You can rent a car at LAX and make the 5 hour trip to Vegas.
are you near the airport in Ontario. It is less than one hour by air to LV. used it several times.
Ontario Airport. I have flown many times out of there.
Do note that CALI is a city on South America. And the closest California airport to Las Vegas is indeed Ontario Airport. Which is in greater Los Angeles and is about 200 miles away from Vegas. So if you will be that far, really, you could go through any of the LA area airports.
Connecting flights from all LA airports to Las Vegas are common and fairly cheap.