how to create advanced search

I'm really stuck in this and i cant find any tutorial or article about this topic.

How about if we have this pattern for search:

[country] AND [category1 OR category2] AND [city1 OR city2] AND [title]
[-radio-] AND [------Checkboxes------] AND [--Checkboxes--] AND [radio]

ok, my code is here. It doest work

html:

<input name="location" value="country_one" type="radio" /> Country 1
<input name="location" value="country_two" type="radio" /> Country 2
<input name="location" value="country_three" type="radio" /> Country 3

<input name="venueA" type="checkbox" value="A" /> selectA
<input name="venueB" type="checkbox" value="B" /> selectB
<input name="venueC" type="checkbox" value="C" /> selectC

functions.php

$metaArgs = array('relation' => 'AND',

                    array(  'key'       =>      'location',
                            'value'     =>      $country,
                            'compare'   =>      '=='
                    ),

                    array('relation' => 'OR',
                        array(  'key'       =>      'venue',
                                'value'     =>      $venueA,
                                'compare'   =>      '=='
                        ),
                        array(  'key'       =>      'venue',
                                'value'     =>      $venueB,
                                'compare'   =>      '=='
                        ),
                        array(  'key'       =>      'venue',
                                'value'     =>      $venueC,
                                'compare'   =>      '=='
                        )
                    )
                );



    $query->set( 'meta_query' , $metaArgs );