how to use multi level user login in codeigniter ?

code:

<?php
    if($this->input->post('login'))
    { 
      $username = $this->input->post('username');
      $password = $this->input->post('password');

      $this->db->select('firstname,password');
      $this->db->from('client');
      $where = "firstname='$username' and password = '$password'";
      $this->db->where($where);
      $query = $this->db->get();
      echo $this->db->last_query();
      $result = $query->result_array();
      $num = $query->num_rows();
      if($num >'0')
      {
        $this->db->select('firstname,password,client_id');
        $this->db->from('client');
        $where = "firstname ='$username' and password = '$password'";
        $this->db->where($where);
        $query = $this->db->get();
        echo $this->db->last_query();
        $result = $query->result_array();
        $this->session->set_userdata('client_id',$result);
        $Session = $this->session->set_userdata('user_type',$result);
        if($session == true)
        {
          redirect('/admins/home');
        }
        else
        {
          redirect('/partner/home');
        }
      }
      else
      {
        echo "<p style='color: red;font-weight: bold;'>Wrong username or password! </p>";
      }
    }
  ?>
  <form method="post">
    <input type="text" name="username" placeholder="Username"/>
    <input type="password" name="password" placeholder="Password"/>
    <input type="submit" name="login" id="login" value="login">
  </form>

This might be duplicate question. Here, I have a table in my database having name client. In this table I m declare a column name user type. I want to login according to user type. for example if my user type is admin then only those user can login who having user type admin similarly if user type is partner then only partner can login. So, how can I do this ? please help me.

Thank You