Return on a quest all these meta_value

You need to use a meta query:

if ( isset( $_REQUEST['src'] ) ) {
    $query = array(
        'post_type'  => 'post',
        'meta_query' => array(
        ),
    );

    if ( isset( $_REQUEST['srcbusiness'] ) ) {
        $query['category_name'] = wp_unslash( $_REQUEST['srcbusiness'] );
    }

    $fields = array(
        'srctype',
        'srcprice',
        'srccity',
        'srcdistrict',
    );

    foreach ( $fields as $field ) {
        if ( isset( $_REQUEST[ $field ] ) ) {
            $meta_query[] = array(
                'key' => $field,
                'value' => wp_unslash( $_REQUEST[ $field ] ),
            );
        }
    }
}