Easy: use a parameterised query:
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlDataAdapter da = new SqlDataAdapter("SELECT MyColumn1, MyColumn2 FROM myTable WHERE mySearchColumn = @SEARCH", con))
{
da.SelectCommand.Parameters.AddWithValue("@SEARCH", "one+two");
DataTable dt = new DataTable();
da.Fill(dt);
myDataGridView.DataSource = dt;
}
}