<?php

$str1 = "nome = stack";
$str2 = "id <5";
$str3 = "senha != over";

$arr1 = preg_split("/([^\w\s]+\s*)/", $str1, -1, PREG_SPLIT_DELIM_CAPTURE);
echo $arr1[0] . $arr1[1] . "\n";
echo $arr1[2] . "\n";

echo "\n";

$arr2 = preg_split("/([^\w\s]+\s*)/", $str2, -1, PREG_SPLIT_DELIM_CAPTURE);
echo $arr2[0] . $arr2[1] . "\n";
echo $arr2[2] . "\n";

echo "\n";

$arr3 = preg_split("/([^\w\s]+\s*)/", $str3, -1, PREG_SPLIT_DELIM_CAPTURE);
echo $arr3[0] . $arr3[1] . "\n";
echo $arr3[2] . "\n";