query specific posts according their custom fields, using sql SELECT

query specific posts according their custom fields, using sql SELECT

My posts have a bunch of custom fields, to help insert and display custom
info easily. I am trying to build a search that would select and display
posts according values of specific 2 custom fields. The first field "type"
is a radio button in my wp-admin, so in database its meta value is always
one word. But second field is checkboxes, so in database meta value has
several words, and I need to get posts that have the one visitor selects.
What I have so far:
Search form, that consists of 2 dropdowns, each for one custom field. I
use it one homepage: pastebin.com/zxPuGduW
A function in functions.php, to select posts according the values set in
dropdowns: pastebin.com/Z6D0GM4q
A results page to show the posts according selections in the dropdowns
form: pastebin.com/KHK0exWn