Modelnya...

<?php
if (!defined('BASEPATH'))
    exit('No direct script access allowed');

class Mservice extends CI_Model {

 	var $table = 'service'; //nama tabel dari database
	var $column_order = array(null, 'no_rangka','no_polisi','model','type','transmission','warna','tahun','km','customer','telephone'
	,'handphone','contact_person','telephone_cp','cabang_penjual','cabang_service','salesman','last_service','job','pekerjaan_utama','program_promo'
	,'status_aktif','hasil_fu1','hasil_fu2','hasil_fu3'); //field yang ada di table user
	var $column_search = array('no_rangka','no_polisi','model','type','transmission','warna','tahun','km','customer','telephone'
	,'handphone','contact_person','telephone_cp','cabang_penjual','cabang_service','salesman','last_service','job','pekerjaan_utama','program_promo'
	,'status_aktif','hasil_fu1','hasil_fu2','hasil_fu3'); //field yang diizin untuk pencarian
	var $order = array('nomor' => 'asc'); // default order


    public function __construct ()
    {
        parent::__construct();
        $this->load->database();
    }


    private function _get_datatables_query()
	{

		$this->db->from($this->table);

		$i = 0;

		foreach ($this->column_search as $item) // loop column
		{
			if($_POST['search']['value']) // if datatable send POST for search
			{

				if($i===0) // first loop
				{
					$this->db->group_start(); // open bracket. query Where with OR clause better with bracket. because maybe can combine with other WHERE with AND.
					$this->db->like($item, $_POST['search']['value']);
				}
				else
				{
					$this->db->or_like($item, $_POST['search']['value']);
				}

				if(count($this->column_search) - 1 == $i) //last loop
					$this->db->group_end(); //close bracket
			}
			$i++;
		}

		if(isset($_POST['order'])) // here order processing
		{
			$this->db->order_by($this->column_order[$_POST['order']['0']['column']], $_POST['order']['0']['dir']);
		}
		else if(isset($this->order))
		{
			$order = $this->order;
			$this->db->order_by(key($order), $order[key($order)]);
		}
	}

	function get_datatables()
	{
		$this->_get_datatables_query();
		if($_POST['length'] != -1)
		$this->db->limit($_POST['length'], $_POST['start']);
		$query = $this->db->get();
		return $query->result();
	}

	function count_filtered()
	{
		$this->_get_datatables_query();
		$query = $this->db->get();
		return $query->num_rows();
	}

	public function count_all()
	{
		$this->db->from($this->table);
		return $this->db->count_all_results();
	}





	/// data sebelumnya..yg menggunakan datatables standar





    function service(){
        return $this->db->get('service');
    }

    function addService($add){
		return $this->db->insert('service',$add);
	}

   //fungsi untuk mendapatkan service, atau mencari primary key milik table service
   	function getService($flag){
		$this->db->where($flag);
		return $this->db->get('service');
	}

	//fungsi untuk mengedit service yang ada didatabase
	function editService($flag,$edit){
		$this->db->where($flag);
		return $this->db->update('service',$edit);
	}

	//fungsi untuk delete data service
	function deleteService($flag){
		$this->db->where($flag);
		return $this->db->delete('service');
	}
}