Capacitively coupled shunt resonator
This kind of circuit very often has a high-Q resonator (R1,C1,L1) matched to low-impedance source and load (Z0) where Z0 is a pure resistance.
Pushed to an extreme (Z0 &lt;&lt; R1), you can estimate the resonant frequency of the network by simply paralleling C1,C2,C3 (add their capacitances). The resulting resonant frequency \$ \frac {1}{2 \pi \sqrt{L_1(C_1+C_2+C_3)}} \$ will be lower than that of \$ \frac {1}{2 \pi  \sqrt{L_1C_1}} \$.

For the somewhat more general case at resonant frequency where Z0 value is similar to R1, you can find the series-to-parallel transform, changing the series network of Z0,C3 to its parallel equivalent Rp,Cp:
\$R_p =\frac { Z_0^2 + XC_3^2}{Z_0} \$  \$XC_p=\frac{Z_0^2 + XC_3^2}{XC_3} \$
The network then becomes (at resonance) a simple, parallel RLC of lower Q than \$ R_1 C_1 L_1 \$.
Keep in mind that far from resonance, these transforms must be re-calculated for every frequency. This network's basic form is a high-pass filter.