<?php
$matches=array();
$text="Вставить теkст";
$reg="/([a-z,A-Z][а-я]+|[а-я]+[a-z]|[а-я]+[a-z][а-я]+)/ui";
$count=preg_match_all($reg, $text, $matches, PREG_SET_ORDER);
for ($i = 0; $i < $count; ++$i) {
    echo $matches[$i][0];
    echo "\t";
}

// your code goes here