<?php
function search($criteria) {
$sql = "SELECT * FROM my_table
WHERE column_1 like :criteria1,
OR column_2 like :criteria2,
OR column_3 like :criteria3
";
$criteria = "%$criteria%";
$stmt = $this->db->prepare($sql);
$stmt->bindParam(':criteria1', $criteria);
$stmt->bindParam(':criteria2', $criteria);
$stmt->bindParam(':criteria3', $criteria);
$stmt->execute();
return($stmt->fetchAll(PDO::FETCH_ASSOC));
}