This I wrote a function for my purpose, it simple but works for me :
function genQuery() {
$row_names = array("name","email","phone","title");
$post_values = array($_POST['name'], $_POST['email'], $_POST['phone'], $_POST['title']);
$num = count($post_values);
$sqlString = "SELECT * FROM t WHERE";
for ($i=0;$i<$num;$i++) {
if (empty($post_values[$i])) { $sqlString.=""; }
if (($post_values[$i]) && ($i==0)) { $sqlString.=" $row_names[$i] LIKE '%$post_values[$i]%'"; }
if (($post_values[$i]) && ($i!=0)) { $sqlString.=" $row_names[$i] LIKE '%$post_values[$i]%'"; }
}
$sqlString = preg_replace("/%'/", "%' AND ", $sqlString);
$len = strlen($sqlString);
$len=$len-4;
$sqlString = substr($sqlString, 0 , $len);
return $sqlString;
}