php extract last n words of string
<?php
$str = "NAME WITH SPACES FIELD1 FIELD2 FIELD3 FIELD4";
preg_match("/(\S+)\s(\S+)\s(\S+)\s(\S+)$/", $str, $matches);
var_dump($matches);
/* array(5) {
[0] => string(27) "FIELD1 FIELD2 FIELD3 FIELD4"
[1] => string(6) "FIELD1"
[2] => string(6) "FIELD2"
[3] => string(6) "FIELD3"
[4] => string(6) "FIELD4"
} */