It's hard to describe noises and diagnose. It could be something simple or complex. If you're ready for an oil change you can have your oil analyzed at a place such as
Blackstone labs who can determine if there's metals in the oil or excessive wear such as a bearing or lifter failure. If the analysis comes back good then you likely have a less major issue such as a ticking injector, fuel pump, spark jump, defective / loose spark plug (happened to my wife's Jeep) or such. Could even be an exhaust leak which if near an exhaust port would sound like a metallic tick as well. Easy to see on a diesel with soot, but harder with a gasser.