Try with following findings,
BindingSource bs = new BindingSource();
bs.DataSource = dataGridView1.DataSource;
bs.Filter = "yourColumnName like '%" + textBox1.Text + "%'";
dataGridView1.DataSource = bs;
or
In Search Text Box Changed event, try the following,
(dataGridView1.DataSource as DataTable).DefaultView.RowFilter = string.Format("Field = '{0}'", searchTextBox.Text);