private void textBox1_TextChanged(object sender, EventArgs e)
{
BindingSource bs = new BindingSource();
bs.DataSource = dgv1.DataSource;
bs.Filter = "[ColumnName1] like '%" + textBox1.Text + "%' " +
"OR [ColumnName2] like '%" + textBox1.Text + "%'" +
"OR [ColumnName3] like '%" + textBox1.Text + "%'" +
"OR [ColumnName4] like '%" + textBox1.Text + "%'";
dgv1.DataSource = bs;
}