search results based on categories or custom fields

I’m not sure how much of a help this will be, but this is a (probably overly convoluted) snippet of code I wrote a few years ago for a shortcode to display posts by category. If nothing else it may at least put you on the right track.

    $featured_posts = get_posts(
                            array(
                                'category' => $atts['cat'],
                                'posts_per_page' => -1
                            )
                        );