Searching in codeigniter

[eluser]tj[/eluser]
hai i need to search a word from a lot of text and display it.it works fine on single word but when we use multiple words separated by a space it doesnot return any value my code is

function fetchblogscount($userid,$tag)
{
$this->db->select('feed_info.id,
feed_info.title,
feed_info.description ');
$this->db->from('feed_info');
$this->db->join('feeds', 'feed_info.feed_id= feeds.id');
$this->db->where('feeds.user_id', $userid);
$this->db->like('title', $tag);
$this->db->or_like('description',$tag);
$q = $this->db->get();
return $q->result_array();
}

tnx in advance