Ho provato cosi'
arr = split(txt, " ")
n_elementi = ubound(arr) - lbound(arr) + 1


Set Rs1 = Server.CreateObject("ADODB.Recordset")
str_query = " SELECT * FROM piani WHERE "

For i = 0 To n_elementi-1

str_query = str_query + "( [Titolo normalizzato] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Comune] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Provincia] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Regione] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Responsabilità secondaria] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [nomi di persona] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Anno di produzione] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Forma (Rapu)] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [norma] Like '%"&arr(i)&"%' "
str_query = str_query + "OR [Datazione fase iter] Like '%"&arr(i)&"%' )"

if i<n_elementi-1 then
str_query = str_query + " AND "
end if

Next