I have a post type in called Publication. I also have few custom field in that post type such as Publication Year, Author...
I want to have a search box with 3 drop-down fields which is All Field, Publication Year, and Author. When user select on All Field, it will search everything all post in this post type, but when user select custom field like Publication Year or Author then it search only that post match with that Publication Year or Author.
I spend 3 days searching on this, but I got no luck so please help to advise me.