php - How to check multiple conditions with regular expression

one text

I have a link : http://example.com/abc?id=1&deco=123&plat=[place]

I use regular expression : /(\&deco=\d*)/ to check parameters &deco.. Now I want to check to add &plat=[place] to the string /(\&deco=\d*)/ in two ways, & and ||, how to do it. Please give me your opinion, Thanks.