Modify SEARCH function in WordPress

Modify the search function on Wordpress site I need to modifiy the script of the search function on [login to view URL] ( EVENT GUIDE AND REVIEW SITE ) When a user is searching, the results of research have to prioritize the Listings ( posts ) over the Events. Exemple : Quartier Latin is a listing. When someone search Quartier Latin, he has to browse 4 pages of events before finding the listing, because all the events that take place here come first. The listing have to come first. The events ( containing the keyword ) have to come second.