change customer password magento

<?php
$customer = Mage::getModel('customer/customer')->load($_REQUEST['custid']);
$oldpassword = $_REQUEST['oldpassword']
$passwordhash = $customer['password_hash'];
$phasharray = explode(":",$passwordhash);
$passpostfix = $phasharray[1];
$completeOldPassword = $oldpassword.":".$passpostfix;
if($completeOldPassword==$passwordhash){
$customer->setPassword($_REQUEST['newpass']);
$customer->save();
}
?>