How about something like this:
PHP Code:
$string = $_POST['search'];
/* split string at spaces */
$tok = strtok($string, " ");
$items = array();
/* fetch every item from the list */
while ($tok !== false) {
$items[]=$tok;
$tok = strtok(" ");
}
/* create SQL statement */
if(count($items)){
/* theres somethign to search for */
$query="SELECT * FROM users WHERE ";
foreach($items as $item){
/* we have no knowledge of how many items they've entered */
if(isset($been_here))
$query .= " OR ";
/* we dont know if they entered "firstname lastname" or "lastname firstname" */
$query .= "firstname LIKE \"%$item%\" OR lastname LIKE \"%$item%\"";
$been_here = 1;
}
}