Custom search page and search by title, content and tag

Can someone review my code , I need to know better solutions or any bug.

Okey ! , I made a PHP file to get search results by parameters and search by title , content and tag

PHP’s head look like:

include('../../../../wp-config.php');
header('Content-type:text/html;charset=utf-8');
$keyword = $_GET['k'];

That I will bring search results by jQuery after.

My main search function to show result from database:

function search($keyword,$mark){
    while($data=mysql_fetch_array($keyword)){
        if($data['post_status']=='publish'){
            echo '<li>#'.$data['ID'].' '.htmlentities($data['post_title']).' ('.$mark.')</li>';
        }
    }
} 

Search by title function : Full keyword (ex : “jack daniels”)

$sql_full_keyword       = "SELECT * from wp_posts WHERE post_title LIKE '$keyword%'";
$search_full_keyword    = mysql_query($sql_full_keyword) or die(mysql_error());
search($search_full_keyword,"Full keyword(s) = '$keyword'");

So i split keyword for next steps like :

$keywords_split         = explode(" ",$keyword);

Search by title function : multi keywords (ex : jack + daniels)

for($i=0;$i<count($keywords_split);$i++){
    $sql_split_keyword      = "SELECT * from wp_posts WHERE post_title LIKE '$keywords_split[$i]%'";
    $search_split_keyword   = mysql_query($sql_split_keyword) or die(mysql_error());
    search($search_split_keyword,"Split keyword = '$keywords_split[$i]'");
}

Search by content function : (same above, but search by content)

for($i=0;$i<count($keywords_split);$i++){
    $sql_split_keyword      = "SELECT * from wp_posts WHERE post_content LIKE '$keywords_split[$i]%'";
    $search_split_keyword   = mysql_query($sql_split_keyword) or die(mysql_error());
    search($search_split_keyword,"Split keyword = '$keywords_split[$i]' (Content)");
}

Than close mysql

mysql_close();

Search by tag function : (using normal wordpress query)

    $tags = str_replace(" ","-",$keyword).",".str_replace(" ",",",$keyword);
    query_posts(array('post_type'=>array('one','two','three') ,'tag' => $tags,'posts_per_page'=>-1));

    while (have_posts()):the_post();
    echo '<li>#'.get_the_ID().' '.get_the_title().'</li>';
    endwhile;

Everything work now and I need someone to review my code, tell me better things or tong …

Full code here : http://snipt.org/zpz0

Thanks