Search and highlight rows in gridview using C#

<form id="form1" runat="server">
        <asp:TextBox ID="RefNo" runat="server"></asp:TextBox>
        <asp:Button ID="btn" runat="server"  Text="search" OnClick="btn_Click"/>
        <asp:GridView ID="Search" runat="server" CssClass="table table-bordered table-hover" AutoGenerateColumns="False" OnRowDataBound="OnRowDataBound">
            <Columns>
                <asp:BoundField DataField="ID" Visible="False" />
                <asp:BoundField DataField="Name" HeaderText="Name" />
                <asp:BoundField DataField="Address" HeaderText="Address" />
            </Columns>
        </asp:GridView>

    </form>

protected void Page_Load(object sender, EventArgs e)
{

    if (!Page.IsPostBack)
    {
        BindData();
    }
}

public void BindData() {
    DataTable dt = new DataTable();
    dt.Columns.Add("ID");
    dt.Columns.Add("Name");
    dt.Columns.Add("Address");
    dt.Rows.Add(1, "karthik", "Bangalore india");
    dt.Rows.Add(2, "prasanth", "Tamilnadu india");
    dt.Rows.Add(2, "sachin", "Mumbai india");
    dt.Rows.Add(2, "sehwag ", "delhi india");

    Search.DataSource = dt;
    Search.DataBind();
}


protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        string seachtext = RefNo.Text.Trim();
        int[] colsToCheck = new int[] {0,1,2};  // columns to be searched [ zero based index ]
        for (int i = 0; i < colsToCheck.Length; i++)
        {
            int colIndex = colsToCheck[i];
            e.Row.Cells[colIndex].Text = Regex.Replace(e.Row.Cells[colIndex].Text, seachtext, delegate(Match match)
            {
                return string.Format("<span style = 'background-color:yellow'>{0}</span>", match.Value);
            }, RegexOptions.IgnoreCase);
        }

    }
}

protected void btn_Click(object sender, EventArgs e)
{
    BindData();
}