Custom search including custom fields

Hello,

i have written this snippet

$args=Array(
'posts_per_page'=>'16',
'cat'=>get_query_var('cat'),
'paged'=>get_query_var('paged'),
'post_type'=>'post',
'meta_key'=>'klient',
'meta_value'=>$_REQUEST['s'],
);

$wp_query=new WP_Query($args);
wp_reset_query(); wp_reset_postdata();

and i need to alter it to show results that have PART of $_REQUEST[‘s’] in title OR content OR custom field named klient.

important is to search only PART of keywords and operator OR.

Thanks in advance